Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - Unrealized Gains On Available-For-Sale Marketable Securities [Member] $ in Thousands	3 Months Ended
	Mar. 28, 2020 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income balance, beginning balance	$ 1,480
Other comprehensive income before reclassifications	95
Amounts reclassified from accumulated other comprehensive income	(6)
Net current period change in other comprehensive income	89
Accumulated other comprehensive income balance, ending balance	$ 1,569